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Phorbol ester‐induced protein phosphorylation and contraction in sphincter smooth muscle of rabbit iris
Author(s) -
Howe Philip H.,
Abdel-Latif Ata A.
Publication year - 1987
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(87)80162-x
Subject(s) - ionomycin , protein kinase c , contraction (grammar) , phorbol , medicine , endocrinology , phosphorylation , extracellular , sphincter , chemistry , muscle contraction , kinase , antagonist , protein kinase a , biology , calcium , anatomy , receptor , biochemistry
Phorbol 12,13‐dibutyrate (PDBu) was employed in studies designed to determine the role of C‐kinase in muscle contraction in the iris sphincter. PDBu induced MLC phosphorylation and contraction in a dose‐ and time‐dependent manner. Maximum responses exerted by PDBu were about 50–60% of that obtained with CCh, and were totally dependent on the presence of extracellular Ca 2+ . PDBu had no effect on basal IP 3 levels, however it blocked the CCh‐stimulated accumulation of IP 3 . PDBu‐induced effects were potentiated by ionomycin, and inhibited by the C‐kinase antagonist H‐7. These results provide further evidence for the involvement of C‐kinase in mediating the sustained phase of the contractile response in the iris sphincter.